1. Field of the Invention
Embodiments of the invention relate to rewinding a real-time group communication session.
2. Description of the Related Art
Wireless communication systems have developed through various generations, including a first-generation analog wireless phone service (1G), a second-generation (2G) digital wireless phone service (including interim 2.5G and 2.75G networks) and third-generation (3G) and fourth-generation (4G) high speed data/Internet-capable wireless services. There are presently many different types of wireless communication systems in use, including Cellular and Personal Communications Service (PCS) systems. Examples of known cellular systems include the cellular Analog Advanced Mobile Phone System (AMPS), and digital cellular systems based on Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), the Global System for Mobile access (GSM) variation of TDMA, and newer hybrid digital communication systems using both TDMA and CDMA technologies.
More recently, Long Term Evolution (LTE) has been developed as a wireless communications protocol for wireless communication of high-speed data for mobile phones and other data terminals. LTE is based on GSM, and includes contributions from various GSM-related protocols such as Enhanced Data rates for GSM Evolution (EDGE), and Universal Mobile Telecommunications System (UMTS) protocols such as High-Speed Packet Access (HSPA).
In any of the aforementioned communication protocols, user equipments (UEs) can engage in communication sessions with other UEs whereby media (e.g., audio media, video media, etc.) is exchanged and played in ‘real-time’. In real-time communication sessions, the value of media drops precipitously as time (e.g., mere seconds of tenths of a second) goes by. For example, audio data (e.g., one or more audio frames) contained in an audio packet received during a phone call typically need to be played relatively soon (e.g., 100-200 ms) after receipt by a target UE, or else the audio data will not have relevance to the phone call. Also, if the audio packet is lost during the phone call, it can take a relatively long time (e.g., several seconds) to re-obtain the lost audio packet (e.g., from the speaker or a server that archives audio packets for the phone call). To mitigate packet loss during real-time communication sessions, mechanisms such as forward error correction (FER) or interleaving are used.
However, if a relatively long outage in a target UE's media occurs during a real-time communication session (e.g., the target UE drives into a tunnel for 8 seconds and loses all media packets transmitted during that period), there is generally little recourse for the target UE in terms of recovering the lost media packets during the outage while also maintaining active participation in the real-time communication session. Some systems are set-up to record or archive real-time communication sessions, in which case the target UE can later attempt to tune to the lost portion from the archived session, but this generally is not possible to implement in a convenient manner while the real-time communication session is ongoing.